INTEGRABILITY, ENTROPY AND QUANTUM COMPUTATION

1999 ◽  
Vol 10 (07) ◽  
pp. 1205-1228 ◽  
Author(s):  
E. V. KRISHNAMURTHY
Keyword(s):  
Quantum Computation ◽  
Quantum Chaos ◽  
Quantum Control ◽  
Dynamical Evolution ◽  
Open Problems ◽  
Quantum Integrability ◽  
Feynman Path Integrals ◽  
Exact Integrability ◽  
Time Arrow ◽  
Computational Systems

The important requirements are stated for the success of quantum computation. These requirements involve coherent preserving Hamiltonians as well as exact integrability of the corresponding Feynman path integrals. Also we explain the role of metric entropy in dynamical evolutionary system and outline some of the open problems in the design of quantum computational systems. Finally, we observe that unless we understand quantum nondemolition measurements, quantum integrability, quantum chaos and the direction of time arrow, the quantum control and computational paradigms will remain elusive and the design of systems based on quantum dynamical evolution may not be feasible.

Liquid-phase adaptive femtosecond quantum control: Removing intrinsic intensity dependencies

2003 ◽  
Vol 118 (8) ◽  
pp. 3692-3701 ◽  
Author(s):  
T. Brixner ◽  
N. H. Damrauer ◽  
B. Kiefer ◽  
G. Gerber
Keyword(s):  
Liquid Phase ◽  
Quantum Control

scholarly journals Dynamic Quantum Games

2021 ◽  
Author(s):  
Vassili N. Kolokoltsov
Keyword(s):  
Real Time ◽  
Repeated Games ◽  
Dynamic Games ◽  
Quantum Control ◽  
Diffusion Processes ◽  
Natural Class ◽  
Quantum Games ◽  
Technical Problems ◽  
Modern Development ◽  
Starting Point

AbstractQuantum games represent the really twenty-first century branch of game theory, tightly linked to the modern development of quantum computing and quantum technologies. The main accent in these developments so far was made on stationary or repeated games. In this paper, we aim at initiating the truly dynamic theory with strategies chosen by players in real time. Since direct continuous observations are known to destroy quantum evolutions (so-called quantum Zeno paradox), the necessary new ingredient for quantum dynamic games must be the theory of non-direct observations and the corresponding quantum filtering. Apart from the technical problems in organizing feedback quantum control in real time, the difficulty in applying this theory for obtaining mathematically amenable control systems is due partially to the fact that it leads usually to rather non-trivial jump-type Markov processes and/or degenerate diffusions on manifolds, for which the corresponding control is very difficult to handle. The starting point for the present research is the remarkable discovery (quite unexpected, at least to the author) that there exists a very natural class of homodyne detections such that the diffusion processes on projective spaces resulting by filtering under such arrangements coincide exactly with the standard Brownian motions (BM) on these spaces. In some cases, one can even reduce the process to the plain BM on Euclidean spaces or tori. The theory of such motions is well studied making it possible to develop a tractable theory of related control and games, which can be at the same time practically implemented on quantum optical devices.

scholarly journals Quantum control of excitons for reversible heat transfer

2019 ◽  
Vol 2 (1) ◽  
Author(s):  
Conor N. Murphy ◽  
Paul R. Eastham
Keyword(s):  
Heat Transfer ◽  
Quantum Dot ◽  
Quantum Control ◽  
Heat Engine ◽  
Laser Pulses ◽  
Heat Current ◽  
Light Emitting ◽  
Laser Dressing ◽  
Working Medium ◽  
Heat Transfers

Abstract Lasers, photovoltaics, and thermoelectrically-pumped light emitting diodes are thermodynamic machines which use excitons (electron-hole pairs) as the working medium. The heat transfers in such devices are highly irreversible, leading to low efficiencies. Here we predict that reversible heat transfers between a quantum-dot exciton and its phonon environment can be induced by laser pulses. We calculate the heat transfer when a quantum-dot exciton is driven by a chirped laser pulse. The reversibility of this heat transfer is quantified by the efficiency of a heat engine in which it forms the hot stroke, which we predict to reach 95% of the Carnot limit. This performance is achieved by using the time-dependent laser-dressing of the exciton to control the heat current and exciton temperature. We conclude that reversible heat transfers can be achieved in excitonic thermal machines, allowing substantial improvements in their efficiency.

scholarly journals Environment-assisted quantum control of a solid-state spin via coherent dark states

2014 ◽  
Vol 10 (10) ◽  
pp. 725-730 ◽  
Author(s):  
Jack Hansom ◽  
Carsten H. H. Schulte ◽  
Claire Le Gall ◽  
Clemens Matthiesen ◽  
Edmund Clarke ◽  
...  
Keyword(s):  
Solid State ◽  
Quantum Control ◽  
State Spin

Quantum control of discrete noise in Josephson qubits

2005 ◽  
Vol 29 (1-2) ◽  
pp. 297-307 ◽  
Author(s):  
A. D’Arrigo ◽  
G. Falci ◽  
A. Mastellone ◽  
E. Paladino
Keyword(s):  
Quantum Control
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